Q-Logic 59042-07 A manual Bandwidth, Port-to-Port Latency

0	3 – Planning
	Performance

3.3.2

Bandwidth

Bandwidth is a measure of the volume of data that can be transmitted at a given transmission rate. A port can transmit or receive at nominal rates of 1-Gbps or 2-Gbps depending on the device to which it is connected. This corresponds to actual bandwidth values of 106 MB and 212 MB respectively. Two 1-Gbps source ports can transmit to the same 2-Gbps destination port. Similarly, one 2-Gbps source port can feed two 1-Gbps destination ports.

In multiple chassis fabrics, each link between chassis contributes 106 or 212 MB of bandwidth between those chassis depending on the speed of the link. When additional bandwidth is needed between devices, increase the number of links between the connecting switches. The switch guarantees in-order-delivery with any number of links between chassis.

3.3.3

Latency

Latency is a measure of how fast a frame travels from one port to another. The factors that affect latency include transmission rate and the source/destination port relationship. Port-to-port latency values on the switch are shown in Table 3-2.

Table 3-2. Port-to-Port Latency

		Destination Rate
Rate	Gbps	1	2
	1	< 1 µsec	< 1 µsec1
Source
	2	< 0.5 µsec	< 0.4 µsec

1Based on minimum sized frame of 36 bytes. Latency increases for larger frame sizes.

59042-07 A 3-5